PROJECT SUMMARY Substantial theoretical work suggests that mental health disorders have their roots in early childhood development, and that symptoms of psychopathology are in part the result of breakdowns in self-regulatory skills that emerge early in life. Yet early predictors of emergent psychopathology, and/or trans-diagnostic phenotypes such as self- regulation, are poorly understood. Utilizing prospective data from a large sample (N=270) of mothers and their children, the current study aims to address this gap by: a) testing the hypothesis that infant negative affect (NA) undermines children's emerging executive functioning (EF), and that NA-associated deficits in EF are one mechanism through which early emotion-regulatory difficulties convey risk for psychopathology at 3 years of age (Aim 1); b) examining whether prenatal stress moderates associations among NA, EF, and psychopathology at age 3 (Aim 2); c) testing whether maternal immune activation during pregnancy and/or child immune activation in infancy mediate the association between maternal prenatal stress and child symptomatology (Aim 3). The results of this research will inform early identification and intervention. The execution of this research plan, in conjunction with the training activities described, will provide the applicant with the skills for an independent, innovative research program aimed at understanding the earliest origins of psychopathology. The training plan assists in enriching her strong background in development with more independence and more training in assessment and observation of psychopathology in childhood. Additionally, it includes strong training in psychoneuroimmunology, including the role of the immune system in psychopathology (in both the mother and child) as well as the mechanisms through which maternal immune activation during pregnancy may influence child risk for psychopathology. Thetraining objectives include:a) learning theory and methods related to the etiology, nosology, and pathogenesis of childhood psychopathology, b) becoming acquainted with clinical assessment issues and diagnostic assignment as it pertains to research application throughout childhood, c) translating her developmental expertise to clinical populations including conceptualizing developmental findings in relation to psychopathology theory and practice, d) gaining hands-on experience conducting research with clinical measures and clinically at risk populations, e) learning theory and methods related to studying the immune system and inflammation-psychopathology associations, f) better understanding the mechanisms through which maternal immune activation during pregnancy may influence the developing brain and, by extension, child risk for psychopathology, g) gaining hands-on experience collecting and analyzing relevant biological samples and learning about contemporary molecular and immunological methods for analyzing inflammatory signaling networks, and h) further training in the responsible conduct of research, including ethical considerations specific to clinical populations, and in i) research writing and dissemination as it pertains to the field of psychopathology, mental health, and psychoneuroimmunology.